Some smell/odor controllers:
When I've been elbow-deep in the septic line feeding the steel ram through, I have used a scrub of used coffee grounds and borax to help descent my skin. Not perfect but helps, and borax (sodium tetraborate) is a mineral that occurs naturally in many areas (like around here for example. Even a town in Central California called Boron, guess why.)
Some aspects of being a "Freegan" (as I've heard it called in Davis, CA) are fun and harmless. Some aspects get you those looks in public. And believe me, Davis has its share. The relatively mild climate, generous social justice orientation of the population, and brilliant STEM students who ended up snapping and taking to the homeless camps make for an interesting vagrant/homeless population. Not only do some of them smell, but Davis had its very own special "Smelly Guy." You could smell him coming half a block away if the breeze was right. I'm not exaggerating at all.
He is your son, but your home is yours. He is how he is by choice, which sucks to say but... that's just the way things are. I don't know what else to say, honestly. Here in the US we have a product you can buy by the gallon, about US$20 per gallon, called "Nature's Miracle." The stuff is amazing, and if you soaked his clothes in it BEFORE WASHING and hung them to dry, repeat treatments might make a difference enough - but you have to use it BEFORE washing with detergent. It doesn't mask smells, it uses enzymes, and it's the wetting/drying that breaks down the smelly organics. NOTE: It can make things smell worse while wet. And how well does it work? Kiddo peed her bed a LOT over the years, we always kept a gallon jug of the stuff in her bedroom, and by the time we moved the mattress was in decent enough shape that we were able to sell it at our pre-moving yard sale. THAT'S how good it is.
Whether the cost of it is worth using over the cost of giving your kid a bit of cash and taking him to a thrift shop, that's your judgement call. And I've put my foot down with Kiddo, and her occasionally questionable personal hygiene awareness, and felt no reason to be nice about it. "NO WAY ARE YOU GETTING IN MY CAR UNTIL YOU CHANGE YOUR PANTS AND UNDERWEAR." Like that.
I wish you strength and compassion in making it through this, and remember that Compassion is not the equivalent of being a pushover when it comes to YOUR needs. Best of outcomes to you.